She was relaxing on a bench in the town's Heritage Park as children frolicked in a nearby playground. Nissopoulos said she counts as a new resident, having moved back to town three years ago after spending more than four years living on Cape Cod.

But most cities and towns either stayed steady or lost population as did the state, which once again demonstrated population growth slower than the rest of the nation.

Springfield lost more than 2,100 people from 2000 to 2007, according to the Census estimate. That's a drop of 1.41 percent, putting the city at 149,938.

These population estimates are important, especially with the 2010 Census looming.

"Transportation dollars and well over 150 other federal funding sources use population numbers as at least part of their formula," said Susan G. Strate, manager of the population estimates program for the Donahue Institute at the University of Massachusetts-Amherst.

The Donahue Institute has a $600,000 grant from the state to get more Massachusetts residents counted in Census estimates and in the 2010 count.

The nation's population grew 7.2 percent from 2000 to 2007 compared with 1.3 percent growth in Massachusetts. That slow rate of growth may hurt the state in the 2010 Census, an actual head count, because the once-a-decade Census will determine how many members of the House of Representatives Massachusetts will have.

The Donahue Institute's job is to make sure as many people as possible get counted in both the estimates and in 2010. But they might not be able to do enough, she said.

"There is no guarantee that we won't still lose a Congressional seat," she said. "I think that scenario might be typical of the Northeast."

The Census Bureau uses vital statistics such as births, deaths and marriages along with building-permit data and other factors to come up with the annual population estimates, said Timothy W. Brennan, executive director of the Pioneer Valley Planning Commission.

Overall, Brennan said Census numbers show the continuing trend of people moving out of city centers such as Springfield and Holyoke to suburbs. Southampton is centrally located to job opportunities in Springfield, Holyoke, Westfield and Northampton.

Springfield's poor reputation for fiscal management and public safety during the past decade may have driven some of that population loss, Brennan said.

David B. Panagore, Springfield's chief development officer, said Brennan has a point.

"But I do think that population count is a lagging indicator," he said.

He said he hopes that revitalization efforts in Springfield, as well as rising gas prices that discourage long commutes, will lead to a population rebound.

"What we need to be doing is concentrating on the 2010 count," Panagore said. "That is the one that is going to count."

Strate said Springfield is undercounted in the census and population estimates. The Donahue Institute has already studied what the Census bureau calls group quarters around the region, including homeless shelters, nursing homes, convents, college dorms and other similar places.

"We believe that we have found 1,431 people living in group quarters in addition to what Census has counted in the City of Springfield," she said.

In Holyoke, the Institute found about 350 more people then the Census had been counting.